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Positive-Unlabelled Learning based Novelty Detection for Industrial Chillers
No full textChiller systems are used in many different applications in both the industrial and the commercial sector. They are considered major energy consumers and thus contribute a non-negligible factor to environmental pollution as well as to the overall operating cost. In addition, chillers, especially in industrial applications, are often associated with high reliability requirements, as unplanned system downtimes are usually costly. As many studies over the past decades have shown, the presence of faults can lead to significant performance degradation and thus higher energy consumption of these systems. Thus, data-driven fault detection plays an ever-increasing role in terms of energy efficient control strategies. However, labelled data to train associated algorithms are often only available to a limited extent, which consequently inhibits the broad application of such technologies. Therefore, this paper presents an approach that exploits only a small amount of labelled and large amounts of unlabelled data in the training phase in order to detect fault related anomalies. For this, the model utilizes the residual space of the data transformed through principal component analyses in conjunction with a biased support vector machine, which can be ascribed to the concept of semi-supervised learning, or more specifically, positive-unlabelled learning
A Comparison Study of Data-Driven Anomaly Detection Approaches for Industrial Chillers
Get PDFFaults in industrial chiller systems can lead to higher energy consumption, increasing wear of system components and shorten equipment life. While they gradually cause anomalous system operating conditions, modern automatic fault detection models aim to detect them at low severity by using real-time sensor data. Many scientific contributions addressed this topic in the past and presented data-driven approaches to detect faulty system states. Although many promising results were presented to date, there is lack of suitable comparison studies that show the effectiveness of the proposed models by use of data stemming from different chiller systems. Therefore this study aims at detecting a suitable data-driven approach to detect faults reliable in different domains of industrial chillers. Thus, a unified procedure is developed, to train all algorithms in an identical way with same data-basis. Since most of the reviewed papers used only one dataset for training and testing, the selected approaches are trained and validated on two different datasets from real refrigeration systems. The data-driven approaches are evaluated based on their accuracy and true negative rate, from which the most suitable approach is derived as a conclusion
Forward Cycle Bases and Periodic Timetabling
No full textPeriodic timetable optimization problems in public transport can be modeled as mixed-integer linear programs by means of the Periodic Event Scheduling Problem (PESP). In order to keep the branch-and-bound tree small, minimum integral cycle bases have been proven successful. We examine forward cycle bases, where no cycle is allowed to contain a backward arc. After reviewing the theory of these bases, we describe the construction of an integral forward cycle basis on a line-based event-activity network. Adding turnarounds to the instance R1L1 of the benchmark library PESPlib, we computationally evaluate three types of forward cycle bases in the Pareto sense, and come up with significant improvements concerning dual bounds
Entwicklung eines Konzepts für eine App zur Überwindung des Medienbruchs beim Stöbern am Regal in der Bibliothek der TH Wildau
No full textZielstellung der Arbeit ist die Entwicklung eines Konzepts für eine Anwendung zur Überwindung des Medienbruchs zwischen physischen und elektronischen Ressourcen am Regal für die Bibliothek der Technischen Hochschule Wildau. Als Ausgangspunkte dafür werden ein bereits bestehender Prototyp sowie die Ergebnisse eines Kickoff-Meetings mit Kolleg/innen der Hochschulbibliothek und des iCampus-Teams der Technischen Hochschule Wildau genutzt.
Zunächst wird dabei die Problematik des Medienbruchs in Bibliotheken erläutert und bestehende Ansätze zur Lösung des Problems skizziert. Es folgen bibliothekarische Vorbetrachtungen zur Standortermittlung, Sacherschließung und Aufstellung in Bibliotheken gefolgt von kurzen technischen Vorbetrachtungen zur Art der App und verwendbaren Frameworks.
Anschließend wird der Ist-Zustand dargestellt. Dazu werden die Ausgangsvoraussetzungen an der Hochschulbibliothek sowie Funktionen und Architektur des bestehenden Prototyps beschrieben.
Schließlich werden die Stakeholder ermittelt und anhand Personas beschrieben, bevor die funktionalen und nicht funktionalen Anforderungen erfasst werden.
Den Hauptteil der Arbeit stellt das Konzept für die Anwendung dar. Im darauffolgenden Kapitel wird die Implementierung der Integration entliehener Bände, der Vormerkfunktion sowie der Durchschaltung zum E-Book beschrieben.
In den Schlussbetrachtungen schließlich wird ein Fazit gezogen, aufgefallene Probleme erläutert und ein Ausblick auf Weiterentwicklungsmöglichkeiten geworfen
Qualitative Wirkungsanalyse Security Awareness in KMU
No full textFührungskräfte und Mitarbeitende sehen sich stolz als Team mit hoher Identifikation und engen Bindungen in ihrem kleinen und mittelgroßen Unternehmen. Doch wie sieht es mit der Informationssicherheit (information security) und dem entsprechenden Bewusstsein (awareness) in deutschen KMU aus? Diese tiefenpsychologische Grundlagenstudie verdeutlicht den Ist-Stand und will gleichzeitig mit ihren Empfehlungen einen Mehrwert für KMU aufzeigen.
Die Studie offenbart, dass der Begriff Informationssicherheit für viele noch diffus ist und nicht selten Fachleuten und Dienstleistern zugeordnet wird. Zukünftig sollte daher die persönliche Wahrnehmung für die eigene Verantwortung für Informationssicherheit am Arbeitsplatz geschärft werden. Zudem verdeutlichen die von den Interviewten genannten relevanten Themen, dass der Awareness-Reifegrad noch deutlich ausgebaut werden kann, denn auf den ersten beiden Plätzen liegen die altbekannten Problemfelder Passwortsicherheit und Phishing-Attacken.
Damit wird deutlich, dass in KMU verstärkt für alle eine Bewusstseinsbildung (awareness raising) für Informationssicherheit stattfinden sollte. Ganzheitliche Awareness-Konzepte, wie im vom BMWi/BMWK geförderten Projekt „Awareness Labor KMU (ALARM) Informationssicherheit“ vorgesehen, oder ein Awareness-Rahmenprogramm mit dokumentierter Strategie kommen bisher in den befragten KMU nicht zum Einsatz. Aktivitäten für mehr Awareness werden bislang oft nur in Form einer reinen Wissensvermittlung verstanden – das greift zu kurz
Hydrogen and Usability of Hydrogen Storage Technologies
No full textScience, technology and politics agree: hydrogen will be the energy carrier of the future. It will replace fossil fuels based on a sufficient supply from sustainable energy. Since the possibilities of storing and transporting hydrogen play a decisive role here, the so-called LOHC (Liquid Organic Hydrogen Carriers) can be used as carrier materials. LOHC carrier materials can reversibly absorb hydrogen, store it without loss and release it again when needed. Since little or no pressure is required, normal containers or tanks can be used. The volume or mass-related energy densities can reach around a quarter of liquid fossil fuels.
This paper is to give an introduction to the field of hydrogen storage and usage of those LOHC, in particular. The developments of the last ten years have been related to the storage and transport of hydrogen with LOHC. These are crucial to meet the future demand for energy carriers e.g. for mobile applications. For this purpose, all transport systems are under consideration as well as the decentralized supply of rural areas with low technological penetration, e.g. regions of Western Africa which are often characterized by a lack of energy supply. Hydrogen bound in LOHC can provide a hazard-free alternative for distribution. The paper provides an overview of the conversion forms as well as the chemical carrier materials. Dibenzyltoluene as well as N-ethylcarbazole - as examples for LOHC - are discussed as well as chemical hydrogen storage materials like ammonia boranes as alternatives to LOHC
Sustainably Produced Hydrogen
No full textThe fossil fuels used to provide energy, such as coal, crude oil and natural gas, are largely responsible for carbon dioxide emissions and other so-called greenhouse gases. Hydrogen gas (H2) can make a key contribution to decarbonization. It can be produced using various processes. Several processes are available to produce hydrogen, such as (i) steam reforming, (ii) cracking process or (iii) electrolysis. Depending on the source of origin, there is a distinction made between different “colours”. Gray, blue, turquoise, yellow and green hydrogen is available, the latter made using Renewable Energies. However, items such as (i) possible variants of hydrogen, (ii) leading export countries or (iii) provision paths to be preferred in the future will be discussed in this paper
Scalable Three-Dimensional Photobioelectrodes Made of Reduced Graphene Oxide Combined with Photosystem I
No full textPhotobioelectrodes represent one of the examples where artificial materials are combined with biological entities to undertake semi-artificial photosynthesis. Here, an approach is described that uses reduced graphene oxide (rGO) as an electrode material. This classical 2D material is used to construct a three-dimensional structure by a template-based approach combined with a simple spin-coating process during preparation. Inspired by this novel material and photosystem I (PSI), a biophotovoltaic electrode is being designed and investigated. Both direct electron transfer to PSI and mediated electron transfer via cytochrome c from horse heart as redox protein can be confirmed. Electrode preparation and protein immobilization have been optimized. The performance can be upscaled by adjusting the thickness of the 3D electrode using different numbers of spin-coating steps during preparation. Thus, photocurrents up to ∼14 μA/cm2 are measured for 12 spin-coated layers of rGO corresponding to a turnover frequency of 30 e– PSI–1 s–1 and external quantum efficiency (EQE) of 0.07% at a thickness of about 15 μm. Operational stability has been analyzed for several days. Particularly, the performance at low illumination intensities is very promising (1.39 μA/cm2 at 0.1 mW/cm2 and −0.15 V vs Ag/AgCl; EQE 6.8%)
3d Printer Heads for Extrusion of Biologicals Gels
No full textProcessing biological materials with 3-dimensional (3D) printers has attracted increasing interest in several research areas. At the same time, off-the-shelf solutions are increasingly available in a wider variety to meet the current market demand. However, most of the available bioprinters are closed source, thus, modifications are quite challenging or require an avoidable consultation process with the manufacturer. Furthermore, the entry prices for basic machines amount to several thousands of euros. Whereas, high-end 3D bio printers with a vast array of features are available for several hundred thousand euros. Due to the immense potential of this tool in the field of biotechnology it is important to extend the availability of this technology for research purposes in terms of adaptability and price. This ongoing work focuses on open-source 3D printer heads with the ability to extrude biological materials. The print heads include several techniques to process low as well as high viscose biomaterials such as agar and gelatin. Additionally, obstacles such as continuous substrate tempering or integration into existing 3D printers are addressed. The work presented is open source and thus freely adaptable to any user’s specific needs. Our goal is to process a diverse range of biomaterials with different print techniques
Bericht Forschung und Transfer 2020
No full textProjekte und Publikationen der TH Wildau aus dem Jahr 2020